Question

How do you solve `0.7x - 0.9( 5- x ) = 4.3`?

Answer 1

`x = 5.5`

Explanation:

`0.7x - 0.9(5-x) = 4.3`

The first thing we do is distribute. As we can see, the `-0.9` is multiplying both `5` and `-x`, so we need to multiply it out.

`0.7x - 4.5 + 0.9x = 4.3`

Now, we "combine like terms." Like terms means the terms where the variables are the same. So all the `x` terms will be put together and all the numbers will be put together.

`1.6x = 8.8`

Now we divide both sides by `1.6` in order to get `x` by itself.
`x = 5.5`

Answer 2

`x = 5.5`

Explanation:

`0.7x−0.9(5−x)=4.3`

Solve for `x`

1) Multiply all the terms on both sides by 10 to get rid of those annoying decimals.

Note: When you can, try to avoid negative numbers, decimals, fractions and (for some reason) odd numbers.

Students make many more mistakes with those headaches than with positive whole (even) numbers.

After you have defeated the decimals by multiplying by 10, you will have this;
`7x - 9( 5 - x) = 43`

2) Clear the parentheses by distributing the `-9`
`7x - 45 + 9x = 43`

3) Combine like terms
`16x - 45 = 43`

4) Add 45 to both sides to isolate the `16x` term
`16x = 88`

5) Divide both sides by 16 to isolate `x`

Note: This division problem is approximately `90 -: 15`, which you know in your head because it is on the clock ("How many quarter hours are there in 90 minutes?")

For Multiple Choice tests
If you have a multiple choice question with exactly one answer that is near 6, just pick the "approximately 6" answer and speed ahead to the next question.

For homework
If this is homework, use a calculator.
Homework is already too long to fool around dividing 88 by 16
https://web2.0calc.com/

Answer:
`x = 5.5`

~ ~ ~ ~ ~ ~

Check

Sub in 5.5 in the place of `x` in the original equation.

`0.7x−0.9(5−x)=4.3`
`0.7(5.5)−0.9(5−5.5)=4.3`

This check isn't worth your time, even with a calculator.
The answer is near the estimate, so it's probably correct.

If it's not correct, you can live with that, especially since not checking it gives you more time for something you actually want to do.

Cheers!